Alyssa Roenigk is a senior writer for ESPN The Magazine and ESPN.com whose assignments have taken her to six continents and caused her to commit countless acts of recklessness. (Follow @ESPN_Alyssa on Twitter).

INDIAN WELLS, Calif. -- Since she arrived here, Serena Williams has been telling us to temper our expectations. In postmatch media conferences, she has said she is easing into her comeback, not placing too much pressure on herself to win matches or perform like the Serena of 14 months ago. She asked us to give her time to return to championship form.

We didn't listen. Her actions during matches seemed to speak more loudly than what she was saying after them.

In her first- and second-round wins in the BNP Paribas Open, she played aggressive, gritty tennis, fighting back from down 3-1 in the first set of her second-round match against Kiki Bertens before winning in a tiebreaker. We had short memories for the unforced errors and uninspired serving, and focused instead on the positives. She showed incredible focus and mental toughness and hit powerful returns. She moved better than she had in the exhibition matches she played before returning to WTA play here at Indian Wells.

Serena Williams' comeback was halted by older sister Venus, who won their third-round matchup at the BNP Paribas Open 6-3, 6-4 on Monday night. In other action on the women's side, Sloane Stephens saw her struggles continue.

With each game, with each match, Williams looked stronger, fitter, more technically sound than she had previously. Heading into Monday night's matchup with her older sister Venus, we all but expected Serena to win -- against a top-10 opponent who played in two Grand Slam finals last year and is contesting her fourth tournament this season. It was too much to ask.

"For me, it was a good match. It was good to play and try to get in the rhythm and get into the swing again," Serena said after the match. "I'm getting there. It's not exactly where I want to be, but I'll get there eventually. I have a lot to improve on. It's good that I don't have to say that this is the best tennis I have ever played and I lost. My room for improvement is incredible. I just have a long way to go, and I'm looking forward to the journey."

On a grander level, this match held a lot of meaning. That is true any time the Williams sisters face each other, and their history here at Indian Wells only compounded the emotion of the night. But in the story of Serena's return to tennis after a 14-month maternity leave, this match will be but a footnote, the first loss she was dealt in what will undoubtedly be a success story punctuated with future Grand Slam wins.

Because she came into this tournament unseeded, it was inevitable she would play a top player early, and that it would be the first true measure of where her game stands right now. Monday against the No. 8 player in the world, Williams looked more like we expected her to look in her first two matches: Like a player who is not in peak form or ready to win tournaments.

"In a way, it's normal she did not win tonight," her coach, Patrick Mouratoglou, told ESPN.com. "If she had won the first tournament, that would have been incredible. But if you know how to use disappointment in a good way, it is great motivation."

During this tournament, Mouratoglou said he and Serena learned a lot about where she is in her comeback and what they need to work on heading into next week's Miami Open.

"The base of her game is there, which is very good news," he said. "But I learned she has to move better. She needs to serve much better than she did. Her body has to be able to recover from matches. The rest of her game needs time and we cannot buy time, so we are going to work as hard as possible to get her back to her highest level with the goal of winning the next Grand Slam."

play

1:10

Venus beats Serena for first time in nearly four years

In the third round in Indian Wells, Venus Williams beats Serena Williams in straight sets.

The day after her first-round match, Mouratoglou said Serena was very sore, which was no surprise considering she hadn't played a match in more than a year. After her second-round win, she had a tougher time recovering and was hurting Monday night. "She was suffering a lot," he said. "I think that hurt her a lot. She was very slow and she was not herself. Venus didn't give her many chances to not be in top shape."

A few times during Monday's match, Williams looked to her player box and motioned toward her coach. "She was asking what she was doing wrong, and I was trying to tell her she was rushing too much," Mouratoglou said. "She was hitting the ball too much in front of her so she couldn't spin the ball. She was rushing with her hands, but she was tired, heavier on her feet and slower than in the other matches, so she couldn't rush with her legs at the same time. Her hands were too early compared to what her legs were doing. I was trying to tell her to calm down and play rallies, but I don't think she could do it tonight."

Both Mouratoglou and Williams gave credit to Venus for playing as well as she has all season and forcing her opponent to rush and make mistakes. This win is Venus' first against her sister since the 2014 Rogers Cup semifinal and, it is the first time she has beaten Serena in straight sets since the 2008 Wimbledon final.

"She put very high pressure on Serena from the start, playing fast and aggressive and with a lot of success," Mouratoglou said. "She played unbelievable."

Williams said she will write down everything she believes she needs to work on heading into Miami, rank them in order of importance and get to work making improvements to her game.

"Each tournament, my goal is just to be better than the last," Williams said. "I definitely don't want to go backward. I want to continue to go forward."